Genes Play Role in Flu Cases

We had a remarkably mild winter this year, both in terms of weather and when it came to cases of the flu. For example, Frederick Memorial Hospital reported 96 positive flu tests in February 2011. This year, the health system’s locations (including primary care physicians, immediate care and off-site facilities) only saw 12 positive flu tests.

But whether the flu is limited in its spread or running rampant, new research conducted in the wake of the pandemic H1N1 flu of 2009 suggests a genetic variation could be responsible for how the same virus can affect patients differently.

During the 2009 H1N1 pandemic, the Centers for Disease Control and Prevention (CDC) estimates about 22 million people had this particular flu strain. Of that number, nearly 100,000 people were hospitalized and nearly 4,000 people died.

Researchers sought to answer the obvious question: what was different about those 100,000 patients who were hospitalized? What made the flu so much worse for them?

One possible answer, identified in a study recently published online in the journal Nature, was the IFITM3 gene. The research team found that the gene plays a role in determining how sick patients (or, in the case of the study, mice) get when exposed to certain strains of the flu.

According to researchers, the gene seems to keep the flu from progressing into a more serious condition. In animals that didn’t have the gene, the flu developed into a viral pneumonia.

Looking back at human data from the H1N1 pandemic, the researchers studied 53 people who were hospitalized in 2009 or 2010 for either the pandemic or seasonal flu strains. Their review found that a small, but scientifically significant, number of the patients (13.2%) had abnormal IFITM3 genes. In fact, 5.7% of the studied group had a specific genetic difference found in just 0.3% of the general population.

Researchers say they know this genetic difference isn’t the only determining factor when it comes to the severity of the flu. Still, Abraham Brass, MD, PhD, of Massachusetts General Hospital in Boston tells Medpage Today there could come a time when a substance that mimics the effect of this gene is identified and could help otherwise vulnerable patients fight off the illness.

For the moment, it appears the worst of this flu season is behind us. Keep up the hand washing, keep your hands away from your face, get plenty of rest, manage stress and make healthy food and drink choices, and with any luck you won’t have to think about the flu again until this fall.